Bathing in the Middle Ages
Contrary to popular belief, the practice of bathing was common in the Middle Ages: villagers and the poor would bathe naked in the rivers while city-dwellers would go to the steam rooms. All European cities had public baths: Paris had twenty-six in the late 13th century.
According to legend, priests on Mount Sapo near Rome burned animals for sacrifice. The remains of these sacrifices, a mixture of animal fat and ash, were tipped into the river where the washerwomen toiled: they noticed that the foaming water in the river made their job easier...
Marseilles soap is made from olive oil to which soda is added; the mixture is blended and cooked (saponification) then the glycerin is removed and used in candlemaking. Crescas Davin was the first master soapmaker of Marseilles in the late 14th century. Genuine Marseilles soap contains at least 72% olive oil.
To publicize them, town criers would let the people know when the water was hot. Cold baths were considered good for the constitution in those days, while only a hot bath and soap could clean the body.